Plasmodium vivax causes recurrent blood stage infections in the absence of an ongoing blood stage cycle through the mechanism of relapse. Relapses occur through the reactivation of dormant liver stage parasites(hypozoites). The mechanism of dormancy and reactivation is unknown. here, the genetic mechanism determining relapse infection in P. vivax will be identified and characterized using the technique of representational difference analysis (RDA). By this technique, genetic material responsible for the relapse phenotype will be amplified and isolated after the subtractive hybridization between genomic DNA of P. vivax isolated from initial infection parasites and its corresponding relapse parasites. This genetic material will be analysed further by probing on the genomic blots of 10 pairs of initial and relapse of P. vivax digested with restriction enzymes. In parallel, these initial and relapse isolates will be characterized and compared for the differences by monoclonal antibodies and gene probes typing. These results will allow the mechanism of relapse occurring in vivax malaria to be uncovered.